Engine speed control



Jan. 4, 1949. c. l. MBONEIL 2,458,398

ENGINE SPEED CONTROL Filed Dec. 8, 1943 2 5116615 511991. 1

INVENTOR.

CHARLES MACA/E/L AITORA/Ex Jan. 4, 1949. g, MacNElL ENGINE SPEED CONTROL 2 Shets-Sheet 2 Filed Den; 1:), 1945 INVENTOR.

CHARLES MAcA/E/L. M451 M FIG.

Arvamaf Patented Jan. 4, 1949 UNITED STATES lATENT OFFICE.

2,458,398 ENGINE SPEED CONTROL Charles I. MacNeil, Glen Ridge, N. J., mi im-Q to Bendix Aviation Corporation, Teterboro, N. J., a corporation of Delaware Application December 8,1943, Serial No. 513,419

' 1 Claim. (01. 2643) 25, 1941, by myself and Donald M. Berges as to all matter common thereto.

An object of the present invention is to provide novel means by which all engines of a group may be accelerated or decelerated simultaneously, each to the degree required for synchronism,

A further object resides in the provision of means for applying a correction to the speed of any power plant that is out of synchronism with a master control or reference speed device.

Another object of the invention is to provide means for applying acorrection to the speed of any power plant that is out of synchronism with a master control or reference speed device and manually operable means within the cabin of the plane for controllin said power plant independently of said master control.

Another object of the invention is to provide motor means responsive to a constant speed generator and an aircraft engine driven variable speed generator for controlling the pitch of the aircraft propellers driven by said engines in accordance with the magnitude and direction of speed differences between the constant speed generator and the respective aircraft engine driven variable speed generators.

Another object of the invention is to provide novel manually operable means for electrically controlling the operation of a propeller pitch control motor responsive to aircraft engine speed, whereby the pitch of such propeller may be'increased or decreased automatically in response to engine speedor independently of the speed of said aircraft engine.

engine to be controlled, so as to maintain said engine in synchronism with said master control,

and means for controlling oneor the other of said windings so as to effect an independent adjustment of said engine.

Another object of the invention is to provide a novel aircraft engine control, including a first master control, a second control responsive to aircraft engine speed, and means driven by said first and second controls for maintaining said aircraft engine in synchronism with said master control,

' and means for terminating the action of one of said controls, whereby said engine speed may be independently adjusted by said other control.

claim. The disclosure, however, is illustrative the terms in which the appended claim is ex- Another object of the invention is to provide master control generator, and the other of said windings energized by a generator driven by the pressed.

In the drawings, wherein like reference characters refer to like parts in the several views:

Figure 1 is a schematic diagram of the electrical features of an illustrative form of the improved synchronizing apparatus. Figure 2 is a sectional view of one of the servounits.

Figure 3 combines the hydraulic connections with another sectional view of one of the servounits, along line 3-3 of Fig. 2; and

Figure 4 is a view at right angles to Figure 3.

In Figure 1 reference characters 90, 9|, 95, and 96 designate the windings of synchronous motors adapted to operate hydraulic servo-units, one of said servo-units -the unit I i-being shown in detail in Figures 2, 3 and 4. The servo-unit to be operated by motor 90, 95 is preferably of identical construction, and each operates to control the adjustment of a governor "speeder spring, such as the governor speeder spring shown at 3| in Figure 2. Such spring opposes the outward movement of governor weights 32, which governor weights in turn maycontrol through a slidable member 9 a hydraulic mechanism for governing the pitch of aircraft propellers in a manner well-known to the art (see Caldwell Fatcut No. 2,032,255 of February 25, 1936). A suitable form of governor for this purpose is particularly illustrated and described in U. S. Patent No. 2,204,640, granted to E. E, Woodward on Whenever the screw shaft 48 is rotated by the means above-described-and the same is true of the corresponding screw-shafts for the other servo-unit-the nut 88' acts to swing lever 8i about pivot 50 as a fulcrum, thus drawing valve rod 82 to the right, or pushing it to the left, depending upon the direction of rotation of the screw-shaft. In either event a path is established for fluid flow from accumulator A (Figure 3) to the central annular chamber of valve 42, 43, and from this central annular chamber the fluid passes into the servo-cylinder (by way of pasings herein, and in the other direction by the action of a governor or centrifugally actuated flyweights such as those shown at 82 and mounted on a rotating head I0 driven by the aircraft engine. Thus the governor is suitably driven in proportion to the engine speed. As the constructionand operation of the governors for each of the units is the same, and is particularly illustrated and described in the Woodward patent referred to, it is believed that no further description thereof is required herein; the governors, per se. not being-claimed herein.

The novel means for adjusting each governor spring '8I, comprises a servo-unit, as above indicated. Each servo-unit (as shown for unit II in Figures 2, 3 and 4) includes a piston 4i, a valve 42, 43 of the plunger type, a pinion 44 rotatable by the linkage 48, "attached to piston rod 48, a rack 49 meshing with pinion 44 and reciprocated thereby, a lever 5i pivotally connected to piston 48 and valve rod 52, and a valve actuating nut 88 having an arm 54 pivotally connecting with lever iii to actuate the valve 42, 48 when shifted along screw '48 in response to rotation of the latter.

Screw 48 of servo-unit II" (and the same is true of the corresponding screw of the servounit operated by motor 80, 98) is adapted to rotate with motor" shaft I08, to effect changes in the speed of the associated engine (by the shifting of the governor 8i, 82); such rotation being brought about in part by the electrical interconnection between engine-driven alternators 91 and 88, on the one hand, and thesynchronous motors 80, and Si, 98, on the other, as shown in Figure 1. The rotative power is also in part derived from a master unit such as a constant speed alternator having a three-phase winding as indicated at 80 in Figure 1. The amountof rotation of each unit (80, 95 and 9|, 88 depends upon the speed diiference, as between the master unit, on the one hand, and eachengine to be synchronized, on the. other.

Should it be desirable, on any special occasion, to accelerate or decelerate a given engine (or engines, less than all) more than the others, this may be accomplished by the operation of certain of the individual control switches shown at 8|, 82, 83, 84 which are conveniently mounted to protect each gear train in the event of any tendency to over-travel (or over-load) associated screw-driven nut (see 58) and a spring (see 2) controls the action of each clutch, to

of the prevent premature slipping.

sage 8| if the valve has shifted to the left, or by way of passage 62, if the valve has shifted to the right). Piston 4i is thus caused to move in one direction or the other, and in doing so forces fluid to flow from cylinder back to the source S by way of the hollow interior of valve rod 52, which hollow interior feeds the return chamber 88 and the return conduit 64.

Movement of piston 4I-and the same is true of the corresponding piston of the other servounit-is translated into rotation of pinion 44, and corresponding rectilinear movement of rack 48, to increase or decrease the load on "speeder" spring 3i, depending upon the direction of movement of the rack. The efiectiveness of fly-weights 321s correspondingly altered, with a resultant movement of the governor valve (see Woodward patent, above referred to) to vary the pitch of the propeller blades, thus altering the load on the engine which is associated with said propeller blades. changes the speed correspondingly.

Moreover it will be seen that I have provided a novel motion amplifying system whereby for every increment of motion of 53, and every position of 58 there is provided an exact change in displacement and change in position of piston rod 48. In other words the mechanism serves as an amplifying device whereby a slight motion or displacement of 58 causes an exact corresponding motion of 48 and 50, but with the addition of sufllcient power so that the motion-of 48 and 80 can do a given task, such as rotating the gear 44, moving the rack 49 and adjusting the compression of the speeder spring 3!. Thus the system disclosed operates to apply a corrective force to-the speed controls of each engine to synchronize their speeds. As piston rod 48 is shifted, a follow-up action occurs by reason of the pivotal movement of lever 5i about fulcrum I0.

,This follow-up action restores valve 42, 48 to neutral.

As previously noted, the winding 80, Figure 1, is the supply circuit of a source of polyphase power which may energize windings 80 and SI with a predetermined frequency selected by the pilot. Such frequency corresponds to the speed 00 at which the pilot desires to operate his engine at a given time. Under such condition, switch 8i and 82 are manually adjusted so as to close the circuit from the winding 80-to the windings 80 and BI, respectively. Likewise switches 88 65 and 84 are adjusted so as to close the circuit from the windings 81' and 98 to windings and 88, respectively.

Restricting the description to one engine, it will be seen that with switch 84 being thus closed and alternator 88 being driven by the engine.

there will be generated power at a frequency corresponding to the speed 01 the engine. The circuit is so arranged that this power being fed into the rotor winding 88 will, if of the same freouency as that being received from the source of Such alteration in load, of course,

. 3 power 88,'result in the magnetic field of 88 rotating at the same frequency and direction as that of 8i with the result that there will be no mechanical force exerted by the windings 8i and 88.. However, should the speed of rotation and the motor to. rotate, moving the gear train I88,

I88, I81, I88, shaft 48 andnut 58 so as to cause the valves 42 and 48 to move so as to control the operation of the arm 48 of the pistonWI as previously described. Such action will cause an adjustment increasing the compression of the speeder spring 8i, whereupon the control member 8 will be adjusted so as to cause a decrease in the pitch of the propeller so that the speed of tlfe engine will increase. The alternator. 88 will then be driven at such a rate of speed as to cause 88 to deliver an increasing frequency, urltil there is no difference in frequency between 8I and its associated winding 86. At 'this point the speed -of the engine will be exactly corresponding to the speed set up by the master source of supply 88.

On the other hand should the frequency of 88 be higher than that of 88 or the frequency of 8i, then 8i will tend to lag behind 88 which will cause the physical rotation of 88 relative to 8i in an opposite direction so as to cause an adjustment decreasing the compression of the speeder spring 8i, whereupon the control member 8 will be adjusted so as to cause an increase in the pitch of the propeller so that the speed of the engine will be decreased until synchronism is obtained. In a like manner the other synchronizers operating from windings 81, 85 and 88 cause the engine on which 81 is installed to maintain the proper speed relationship with the master source of supply 88,

and since both engines are running at speeds that correspond exactly to that set up by the master source of supply at 88, then both engines'must be running at identical speeds in relation to one another.

Should for some reason the pilot wish to cause I:

short-circuiting the windings of 8i, as indicated diagrammatically at Figure 1. The resulting short-.circuiting of the windings 8|, together with the continued energization of windings 88 by means of alternator 88 will cause the windings 8i, 88, to operate as a wound rotor induction motor whereupon the energization of the winding 8I' will lag behind the energization of winding 88 causing a relative mechanical rotation in one direction between 8| and 88. Such action in turn will result in the operation of the servo mechanism by means of shaft I88 and its resulting gear train, so as to cause the governor setting to be changed decreasing the tension of speeder spring I! for effecting the control member 8 so as to increase the pitch of the propeller and the desired lowering of the speed of the engine. The switch 8i may be likewise adjusted so as to secure similar operation between the windings 88 and 88.

If it is now desired to increase the engine speed above that set up at 88, or in other words, to secure a reversal of rotation of 88 from that direction in which it was rotated in the preceding paragraph, this may be readily accomplished by keeping the switch 82 in the position where the winding 8i is energized by winding 88. Then by a corresponding change of the switching arrangement of 84, the winding 86 may be short-circuited so that the winding 88 will act as a rotor of a wound rotor induction motor. The electromagnetic forces of the windings 8| will impart a reverse rotation to the rotor 88 from that described in the preceding paragraph for decreasing the pitch of the propeller and increasing the engine speed. The switch 88 may be likewise thrown so as to short-circuit the winding so that a similar action can be obtained between 85 and 88. Alike effect may, of course, be accomplished by varying the energization of the respective windings in any suitable manner, such as by varying the resistance between the windings 88, 8 I, 88 or 88 and the respective supply circuits.

Moreover when the pitch of a propeller has been. adjusted through manual operation of the switches 8I-88 or 82-84 to the position desired, the rack 48 may be locked in such adjusted position by the opening of switches 8 I-83 or 82-84, as shown in Figure 1.

As another application of my invention the coni trol member 8 may actuate a servo valve of the type shown in the said abandoned joint application, Serial No. 416,578 of Donald M. Berges and myself, filed October '25, I84I. Thus the herein control member 8 may control through the servo valve provided therein a servo motor for adjusting the position of an engine throttle to increase or decrease the speed of the engine instead of controlling the pitch of a propeller, as previously described. Moreover the master constant speed.

alternator may be driven by the master engine, as indicated in the above application, Serial No. 416,578 or the same may be driven by a separate power unit. The control member 8 may similarly be utilized for the adjustment of any other suitable engine control.

Although only several applications of the invention have been illustrated and described, va-

rious changes in the form and relative arrangement of the parts, which will now appear to those skilled in the art, may be made without departing from the scope of the invention. Reference is, therefore, to be had to the appended claim for a definition of the limits of the invention.

What is claimed is:

Means for varying the speed of a propellerdriving internal combustion engine, comprising a governor for controlling the speed of said engine, said governor having a speeder spring forming a part thereof, means including a hydraulic servomotor for varying the loading of said speeder spring, said servo-motor including a hydraulic control valve normally occupying a neutral position, motion translating means for shifting said valve, electrical means for actuating said motion windings, and manually operable means located within reach of the pilot of the craft when the latter is in flight for alternately rendering the ineflective, whereby the speed of said controlled energization of one or the other of said windings,

engine may be independently regulated by the pilot.

CHARLES I. MACNEIL.

REFERENCES CITED The following references are of record in :the file of this patent:

UNITED STATES PATENTS Number Name Date 689,186 Heisler Dec. 17, 1901 819,028 Stanley J Apr. 24, 1906 871,513 Lohr Nov. 19, 1907 1,570,505 Laughlin Jan. 19, 1926 1,671,463 Boddie May 29, 1928 Number 8 Name Date Charlton Jan. 5, 1932 Herr Apr. 12, 1932 Simmen Jan. 2, 1934 Wettstein Oct. 16, 1934 Artsay Oct. 23, 1934 Schliipfer Nov. 9, 1937 Martin Jan. 17, 1939 Kalin June 18, 1940 Brady Oct. 15, 1940 Martin Aug..12, 1941 Martin Oct. 28, 1941 Dickey Nov. 4, 1941 Martin Nov. 17, 1942 Drake May 18, 1943 Martin Oct. 26, 1943 French Apr. 24, 1945 

